Tonewoods and Shapes for Resonance? - Page 2 - diyAudio
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Old 19th December 2007, 03:26 PM   #11
patch is offline patch  United States
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Thanks hermanv, I see what you mean. I am getting a dull result with a sphere made of two very large wooden bowls glued rim to rim, about 1.5 cubic feet under there. Looks great to my kids, but I only got the bowls barely listenable. Instead of bass it rather sounds like a truck changing gears, the otherwise stable jbl/consumer-grade driver beams tin at lower frequencies, crossed or not.

Maybe I need to install my under-fluxed Jensen 15" at the open end of one, to look like a short horn-in-reverse. Then again, not.
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Old 19th December 2007, 04:09 PM   #12
hermanv is offline hermanv  United States
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Quote:
Originally posted by sdclc126
IMHO loudspeaker cabinets should be seen and not heard.
<snip>
I believe it is physically impossible for a cabinet to improve the sound of a speaker - its vibrations are a passive reaction to the movement of the transducers, and resultant sound is an artifact of cabinet rather than transducer characteristics. One might hear "more" bass, but it will be unrealistic and distorted bass.
<snip>
Drivers reproduce music - cabinets do not.
In general I agree, but it not impossible to visualize a situation where a given speaker design has a notch and the cabinet resonant at that notch frequency fills it in.

Like all other narrow filters, regardless of how they are made, making the Q the same is vitally important. In this case the resonant rise and fall times must match exactly for this to work. A very difficult feat, but not impossible.

If I need a narrow filter I'll stick to ones in my crossovers, thank you, but not dismiss alternatives out of hand. As I said earlier Sonus Faber is one believer in cabinet resonance, their speakers are arguably in the top tier of commercial designs.
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Old 19th December 2007, 05:29 PM   #13
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hermanv -

I did not mean to sound as though I was dismissing alternative speaker theories out of hand - it was based on experience and my understanding of physics.

I would not second guess what a manufacturer such as Sonus Faber is doing - however what I would do is want to listen to, and measure, both a resonating speaker (cabinet) and a non-resonating one of the same design; can't be done because they don't make both, but for me that would be the litmus test.

Panomaniac -

Yes there is no one way to achive "Nirvana" because we all have different tastes and what is Nirvana to one is garbage to another. The beauty of DIY is that we can make speakers to sound the way we WANT them to, and we all want something different.

I am speaking from my approach - I want to hear reproduced sound that is as faithful to the original as possible - nothing added, nothing taken away. I want to hear a reproduced violin that sounds no different from a real violin, and that extrapolates out to every other musical instument, type of music, etc.

Back in the 80s I purchased a set of devices by a company called Microscan, that attached to the back of loudspeaker cabinets. They converted cabinet resonance into heat - conversion of mechanical energy into heat energy. I listened to a set of good speakers that had the device on one and not on the other. There was a decided reduction of midbass "boom" in the speaker with the device - the difference was quite audible, going back and forth from one speaker to the other. For me the preference was obvious.

As for deliberately tuning a cabinet for resonance, I do see merit if it compensates for a dip in frequency response of the drivers, but not if it creates a rise in the response curve. I am still guarded about this sort of "tuning" - again because of the basic physics - cabinet panels are not transducers and when they vibrate they produce their own secondary sound outside of the reproduced music signal - this, at least to me, by definition is not "high fidelity."
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Old 19th December 2007, 05:48 PM   #14
Nordic is offline Nordic  South Africa
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Once again in violins the "cabinet" IS the transducer.....
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Old 19th December 2007, 06:30 PM   #15
Bobken is offline Bobken  United Kingdom
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Default Speakers as musical instruments!

Although I haven't listened to any of them, apparently Bosendorpher deliberately exploit cabinet resonances, and the properties of the materials used (like wood), in their quite expensive loudspeakers.

For anyone who may not know, they also make very well thought-of grand pianos, so they should know a thing or two about this subject.

Regards,
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Old 19th December 2007, 06:36 PM   #16
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I suspected this argument would come up.

A musical instrument and a loudspeaker are not the same. In a violin there is no conversion of an electrical signal into mechanical movement. In the case of string instruments, the wooden chamber resonates and amplifies the sound of the strings and gives a particular character to the instrument - making the chamber out of a different material imparts a different sound quality to the instrument. But ALL of that is recorded in the studio and reproduced by the drivers in a loudspeaker. Anything a cabinet adds to that is something that was not in the orignal recording!

To say that you need a resonating wooden speaker cabinet to accurately reproduce a violin is like saying you need a metal cabinet to accurately reproduce a trumpet. Indeed, how can transducers reproduce the sound of any instrument when they are not shaped or built like any of them?

A loudspeaker cabinet at best could mimic perhaps one instrument, but it can't be a catch-all - whatever resonance it has will react to the entire music signal at its resonant frequency, imparting characteritics to any and all musical instruments playing in the recording in that region, characteristics those instruments do not generate by themselves.
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Old 19th December 2007, 06:54 PM   #17
Andy G is offline Andy G  Australia
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Default Re: Speakers as musical instruments!

Quote:
Originally posted by Bobken
Although I haven't listened to any of them, apparently Bosendorpher deliberately exploit cabinet resonances, and the properties of the materials used (like wood), in their quite expensive loudspeakers.

For anyone who may not know, they also make very well thought-of grand pianos, so they should know a thing or two about this subject.

Regards,

I have heard them. They reproduces piano VERY well !!

no matter what instrument is playing !!!
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Old 19th December 2007, 07:00 PM   #18
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Old 19th December 2007, 07:09 PM   #19
Pano is offline Pano  United States
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Me too!
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Old 20th December 2007, 06:20 AM   #20
Svante is offline Svante  Sweden
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Here are two articles on deliberately resonant "loudspeakers". They were used for amplification of instruments, as I recall it.

http://www.speech.kth.se/prod/public..._4_087-096.pdf

http://www.speech.kth.se/prod/public..._1_063-083.pdf
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